System and method for easy removal of hydraulic hammer bushing

ABSTRACT

A hydraulic hammer having a front head and a lower bushing is disclosed. Also disclosed is a system and method for easily removing the lower bushing from the front head. The front head of the hydraulic hammer may define a bore therein and an inner surface of the bore may have a first taper. The lower bushing of the hydraulic hammer may be capable of being positioned within the bore of the front head and an outer surface of the lower bushing may have a second taper, with the first taper substantially following the second taper.

TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates to hydraulic hammers and, moreparticularly, relates to a system and method for easy removal of lowerbushings of hydraulic hammers.

BACKGROUND OF THE DISCLOSURE

Hydraulic hammers are widely used on work sites to break up or demolishlarge hard objects, such as, rocks, concrete, asphalt, frozen ground,etc., before such objects can be moved away. Hydraulic hammers can bemounted to work machines like back hoes or excavators, or they can behand-held. In operation, high pressure fluid drives a piston of thehydraulic hammer to strike a work tool, such as a tool bit, which thenstrikes the hard object to be broken.

Generally speaking, the work tool is retained within a lower and anupper bushing of the hydraulic hammer, and the upper and the lowerbushings in turn are enclosed within a bore of a sleeve or housing, alsocommonly referred to as a front head. Because of repeated impact of thework tool on hard objects, the lower bushing of the hydraulic hammerexperiences extreme loads during operation. Such extreme loads oftencause the lower bushing to wear out. As such, the lower bushing may needto be replaced or serviced several times during the product life of thehydraulic hammer. In order to remove the lower bushing from the fronthead, a cross pin connecting the front head and the lower bushingtogether may be detached and, the lower bushing may be pulled or pushedout from the front head for replacement or for servicing.

Conventionally, the outer surface of the lower bushing and an innersurface of the bore of the front head are designed parallel to eachother such that when the lower bushing is pushed (or pulled) out forremoval from the front head, the clearance between the lower bushing andthe front head remains the same until the lower bushing is completelyremoved from the front head bore. As this clearance is small, contactbetween the lower bushing and the front head may occur, thereby makingthe removal of the lower bushing difficult. In certain instances, thelower bushing may change its shape during usage, causing the surfaces ofthe lower bushing and the front head to bind during removal, therebyexacerbating the removal process of the lower bushing. This difficultyin removing the lower bushing from the front head not only increases theservicing time of the lower bushing, it also adds to the labor cost andmay even corrode the front head somewhat, which in turn may lead toreplacement of the hydraulic hammer altogether.

It would accordingly be beneficial if an improved mechanism foreffectively removing the lower bushing from the front head weredeveloped. It would additionally be beneficial if such a mechanismavoided contact between the front head and the lower bushing duringremoval.

SUMMARY OF THE DISCLOSURE

In accordance with one aspect of the present disclosure, a hydraulichammer is disclosed. The hydraulic hammer may include a front headdefining a bore therein, an inner surface of the bore having a firsttaper and, a lower bushing capable of being positioned within the bore,an outer surface of the lower bushing having a second taper, the firsttaper substantially following the second taper.

In accordance with another aspect of the present disclosure, a lowerbushing is disclosed. The lower bushing may include an outer wall and aninner wall. The inner wall may define a bore therein and the outer wallmay have a tapered surface such that the outer wall and the inner wallare non-parallel to one another.

In accordance with yet another aspect of the present disclosure, amethod of removing a lower bushing from a front head of a hydraulichammer is disclosed. The method may include providing (a) a front headdefining a bore therein, the bore having an inner surface with a firsttaper; and (b) a lower bushing capable of being positioned within thebore, the lower bushing having an outer surface with a second taper and,the inner surface of the bore and the outer surface of the lower bushingdefining a clearance therebetween, the clearance remaining constant inan installed state of the lower bushing. The method may also includeremoving the lower bushing from the front head by increasing theclearance as the lower bushing extends out of the front head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary schematic illustration of a hydraulic hammerattached to a work machine, in accordance with at least some embodimentsof the present disclosure;

FIG. 2 is a cross-sectional view, in cut-away, of the hydraulic hammerof FIG. 1, in accordance with at least some embodiments of the presentdisclosure;

FIGS. 3A-3C are schematic illustrations, in cut-away, of a lower bushingand a front head of the hydraulic hammer of FIG. 1 illustrating removalof the lower bushing with respect to the front head, in accordance withat least some embodiments of the present disclosure;

FIGS. 4A and 4B are tabular illustrations indicating exemplary clearancemeasurements between the front head and the lower bushing as the lowerbushing is removed from the front head;

FIG. 5 is an exemplary flowchart outlining the steps for removing thelower bushing from the front head of the hydraulic hammer;

FIG. 6A is a perspective view of an exemplary lower bushing, inaccordance with at least some embodiments of the present disclosure;

FIG. 6B is a top view of FIG. 6A;

FIG. 6C is a cross-sectional view taken along lines A-A of FIG. 6B; and

FIG. 6D is a front view of FIG. 6A.

While the present disclosure is susceptible to various modifications andalternative constructions, certain illustrative embodiments thereof,will be shown and described below in detail. It should be understood,however, that there is no intention to be limited to the specificembodiments disclosed, but on the contrary, the intention is to coverall modifications, alternative constructions, and equivalents alongwithin the spirit and scope of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides a system and method to effectivelyremove a lower bushing from a front head of a hydraulic hammer. In thisrespect and referring to FIG. 1, an exemplary work machine 2 isschematically shown in accordance with at least some embodiments of thepresent disclosure. A hydraulic hammer 4 may be attached to a boom 6 ofthe work machine 2 to operate the hammer. A work tool 8, such as, a toolbit, may in turn be attached to the hydraulic hammer 4 for impacting asurface (or an object on surface) 10. In at least some embodiments, thework machine 2 may be an excavator, although in other embodiments, thework machine may be a back loader, a mini excavator, a skid steer or anyother type of work machine suitable for attaching and using thehydraulic hammer 4. In at least some other embodiments, the hydraulichammer 4 may not be attached to the work machine 2 and rather, may be ahand-held device or may be connected to some other suitable base.Furthermore, the hydraulic hammer 4 may be powered by a pneumatic or ahydraulic fluid source, although other types of demolition hammerspowered by other types of sources may be employed as well.

It will be understood that only those components that are essential fora proper understanding of the present disclosure are shown and/ordescribed herein. Nevertheless, several other components that arecommonly employed in combination or conjunction with the work machine 2and the hydraulic hammer 4 are contemplated and considered within thescope of the present disclosure.

Turning now to FIG. 2, a partial cross-sectional view of the hydraulichammer 4 is shown, in accordance with at least some embodiments of thepresent disclosure. As shown, the hydraulic hammer 4 may include ahousing or front head 12 defining a chamber or bore 14. In at least someembodiments, the front head 12 may include an upper end 16 and a bottomend 18. Furthermore, the front head 12 may be configured or constructedas a single integral piece or may be formed of multiple pieces connectedtogether in operational association. Within the bore 14, a piston 20 maybe operatively disposed to translate along an axis 22 to drive the worktool 8. Specifically, the work tool 8 may have a first end 24 that maybe configured and positioned within the front head 12 to be struck bythe piston 20 and, a second end 26 that may extend from the bottom end18 of the font head to impact the surface 10 or objects positionedthereon. Particularly, the work tool 8 may be positioned and slidablyretained within a lower bushing 28 and an upper bushing 30, both ofwhich may be fixably held within the front head 12. The lower bushing 28may be connected to the front head 12 by way of one or more cross pins32. The lower bushing 28 is described in greater detail below withrespect to FIGS. 6A-6D.

Notwithstanding the components of the hydraulic hammer 4 describedabove, it will be understood that several other components that have notbeen described, such as, various pins and retainers for retaining theupper bushing 30 and the work tool 8 within the front head 12 and forconnecting those components relative to one another and the lowerbushing 28, various sealing rings, etc. are contemplated and consideredwithin the scope of the present disclosure.

Referring now to FIGS. 3A-3C, schematic illustrations of the front head12 and the lower bushing 28 are shown, in accordance with at least someembodiments of the present disclosure. Specifically, each of the FIGS.3A-3C show various stages of removal of the lower bushing 28 relative tothe front head 12. More specifically, FIG. 3A shows the lower bushing 28in an installed position within the front head 12, while FIG. 3B showsthe lower bushing partially removed from the front head and FIG. 3Cshows the lower bushing completely removed from the front head.

In order to facilitate an effective removal of the lower bushing 28 fromthe front head 12, each of the lower bushing 28 and the front head 12may be provided with a tapered surface. With respect to the lowerbushing 28 in particular, an outer surface (or wall) 34 of the lowerbushing may be tapered (e.g., have a conical or substantially conicalsurface) and the tapering may extend along an entire (or substantiallyentire) length of the lower bushing. In at least some embodiments, theouter surface 34 may be tapered by an angle Θ (See. FIG. 3C) of abouthalf a degree to about one degree with respect to a vertical surface orline 36. In other embodiments, the degree (e.g., angle Θ) of tapering ofthe outer surface 34 of the lower bushing 28 may vary. Thus, due to thetapered outer surface 34, the lower bushing 28 may have a broader bottomportion 38 and a narrower top portion 40 for facilitating removal (e.g.,by pulling from the bottom or pushing from the top) of the lower bushingfrom the bottom of the front head 12. It will be understood that in atleast some embodiments, the lower bushing 28 may be removed (e.g., bypulling from the top or pushing from the bottom) from a top portion ofthe front head 12 in which case, the lower bushing may have a broadertop portion 40 and a narrower bottom portion 38.

Furthermore, the tapered lower bushing 28 may be tightly held and fittedwithin the similarly tapered bore 14 of the front head 12. Specifically,the length of the bore 14 of the front head 12 that may be in contactwith the outer surface 34 of the lower bushing 28 during a normalinstalled state may be tapered in at least some embodiments. The degreeof tapering of the bore 14 may be similar to the degree of tapering ofthe outer surface 34 of the lower bushing 28. Thus, in at least someembodiments, the bore 14 and, particularly, an inner surface 35 of thebore, may be tapered by an angle Θ′ of about half a degree to about onedegree relative to a vertical surface or line 42 and may have a broaderbottom bore portion 44 and a narrower top bore portion 46 to mimic thebroader bottom portion 38 and the narrower top portion 40, respectively,of the lower bushing 28.

By virtue of designing the lower bushing 28 and the bore 14 of the fronthead 12 with tapered surfaces, easy removal of the lower bushing fromthe front head may be facilitated. Specifically, due to the tapering ofthe lower bushing 28 and the front head 12, a clearance (e.g., the gapbetween the front head and the lower bushing) 47 may increase as thelower bushing is pulled (or pushed) out from the front head forservicing or replacement. This increase in the clearance 47 between thelower bushing 28 and the front head 12 as the lower bushing is removedfrom the front head may prevent any contact between the lower bushingand the front head even when the shape of the outer surface 34 of thelower bushing changes during usage, thereby making the removal of thelower bushing easy.

Furthermore, during removal of the lower bushing 28 from the front head12, the lower bushing may only need to be pulled (or pushed) by a smalldistance D (See. FIG. 3A) from the top bore portion 46 beyond which theclearance 47 between the lower bushing and the front head starts toincrease and the lower bushing may be easily removed or may possiblyeven slide down by itself. This is in contrast to conventional designswhere both the lower bushing 28 and the front head 12 have cylindricalparallel surfaces with the clearance 47 being constant, which can resultin binding between the lower bushing and the front head and, thedistance D may be equal to D′, thereby requiring the lower bushing to bepulled (or pushed) through a greater distance making the removal moredifficult. Additionally, given that the taper of the outer surface 34 ofthe lower bushing 28 follows (or substantially follows) the taper of thebore 14, the clearance 47 between the front head 12 and the lowerbushing may remain substantially the same through the entire length ofthe lower bushing during normal installed operation.

Thus, as the lower bushing 28 is removed from the bore 14 of the fronthead 12, the clearance 47 between the lower bushing and the front headgradually increases. An exemplary increase in the amount of theclearance 47 as the lower bushing 28 is removed from the front head 12is shown in a tabular form in FIG. 4A. It will be understood thatalthough in the present embodiment, both the front head 12 and the lowerbushing 28 have been described as having tapered surfaces, this need notalways be the case. Rather, in alternate embodiments, only one of thefront head 12 and the lower bushing 28 may be tapered. Furthermore, thedegree of taper may vary.

Referring now to FIGS. 4A and 4B, exemplary measurements of theclearance 47 between the front head 12 and the lower bushing 28 as thelower bushing is removed from the front head are shown in tabular form,in accordance with at least some embodiments of the present disclosure.It will be understood that the measurements provided in FIGS. 4A and 4Bare merely exemplary and these measurements may vary in otherembodiments depending upon several factors, such as, dimensions of thefront head 12 and the lower bushing 28, the amount of tapering of thefront head and the lower bushing, etc. Furthermore, FIG. 4A shows theclearance measurements between the front head 12 and the lower bushing28 with tapered surfaces, as described above and, FIG. 4B shows theclearance measurements in a conventional cylindrical lower bushing andfront head design.

As shown in FIG. 4A, a left column 48 shows the amount of movement(e.g., the distance D of FIG. 3A) of the lower bushing 28 from the topbore portion 46 of the front head 12 during removal of the lower bushingfrom an installed position, while a right column 50 shows the amount ofincrease in the clearance 47 as the lower bushing is removed. Thus, aninitial or installed position 52 when the lower bushing 28 is completelyinstalled within the front head 12 shows a movement of about zero inches(0″) of the lower bushing relative to the front head and the clearance47 (shown in block 54) of about a one tenth of a millimeter (0.1 mm). Asthe lower bushing 28 is removed from the front head 12 by pushing (orpulling) the lower bushing relative to the front head, therebyincreasing the distance D from about one inch (1″) to about four inches(4″), the clearance 47 between the front head and the lower bushinggradually increases from about one fourth of a millimeter (0.25 mm) toabout one millimeter (1 mm), as evidenced by rows 56 through 62,respectively.

These measurements are in contrast to the measurements shown in FIG. 4Bin which a left column 64 is identical to the left column 48 of FIG. 4Ashowing the amount of movement (e.g., the distance D) of the lowerbushing 28 from the top bore portion 46 of the front head 12 and, aright column 66 shows the measurements of the clearance 47 between thefront head and the lower bushing as the lower bushing is removed furtheraway from the front head. It can be seen that as the lower bushing 28 isremoved from the front head 12, thereby increasing the distance D fromabout zero inches (0″) to about four inches (4″), the clearance 47between the front head and the lower bushing 28 remains the same atabout one tenth of a millimeter (0.1 mm), as shown by rows 68-76.Therefore, with no increase in the clearance 47 between the front head12 and the lower bushing 28, the lower bushing has to be pushed (orpulled) out completely (e.g., with D=D′) to remove the lower bushingfrom the front head in conventional designs, thereby making the removaldifficult and time consuming.

Turning now to FIGS. 6A-6D, an exemplary one of the lower bushing 28 isshown, in accordance with at least some embodiments of the presentdisclosure. Specifically, FIG. 6A shows a perspective view of the lowerbushing 28, while FIG. 6B shows a top view thereof. Relatedly, FIG. 6Cshows a cross-sectional view taken along line A-A of FIG. 6B, while FIG.6D shows a front view of the lower bushing 28. As shown, the lowerbushing 28 may be a cylindrical or substantially cylindrical structurecapable of being positioned within the front head 12 and further capableof receiving and securing the work tool 8 for operation.

In particular, the lower bushing 28 may include the outer wall 34 and aninner wall 78, the inner wall defining a bore 80 within which the worktool 8 may be received and secured. Furthermore, as described above, andas clearly shown in FIG. 6C, the outer wall 34 of the lower bushing 28may be tapered, while the inner wall 78 need not be tapered (e.g.,vertical). Thus, the outer and the inner walls 34 and 78, respectively,may be non-parallel to one another, as shown by arrows 81. As mentionedabove, the outer wall 34 may be tapered to mimic a taper in the bore 14of the front head 12 for facilitating an easy removal of the lowerbushing 28 therefrom.

Additionally, the outer wall 34 may include a plurality of elongatedrecesses 82, positioned at (or substantially at) ninety degrees to oneanother. Any one of the recesses 82 may be employed for inserting thecross-pins 32 to secure the lower bushing 28 to the front head 12.Typically, only one of the cross-pins 32, and thus, only one of therecesses 82 is used for securing the front head 12 and the lower bushing28. However, since wear on the inner surface (e.g., the inner wall 78)of the lower bushing 28 may not be even (the front and the back innersurfaces may wear more than the side surfaces, or vice-versa), the lowerbushing may be rotated by ninety degrees (and the recess 82 at thatninety degree angle may be used to secure the front head 12 and thelower bushing) to extend the operating life of the lower bushing beforereplacement may be needed.

The outer wall 34 may further include one or more chamfered orcircumferential grooves 84 flanked on either sides by additional grooves(e.g., square grooves) 86. The chamfered grooves 84 may be employed forreceiving lubricant from the front head 12 and for supplying thatlubricant (e.g., grease) to lubricate the surface between the inner wall78 and the work tool 8. Specifically, the lubricant received from thefront head 12 may fill around the chamfered grooves 84 and may then flowto the surface of the inner wall 78 by way of a plurality (e.g., fourapertures) of apertures 88. The additional grooves 86 may be employedfor holding sealing mechanisms (such as, O-rings) for containing thelubricant within the chamfered grooves 84, thereby preventing thelubricant from flowing along the outer wall 34 of the lower bushing 28.

Notwithstanding the features of the lower bushing 28 described abovewith respect to FIGS. 6A-6D, it will be understood that other featuresthat are commonly provided in lower bushings and specifically for lowerbushings for use with hydraulic hammers, are intended and consideredwithin the scope of the present disclosure.

INDUSTRIAL APPLICABILITY

In general, the present disclosure sets forth a system and method foreasily removing a lower bushing from a front head of a hydraulic hammerfor replacement or servicing. One or both of the front head and thelower bushing may have a tapered or otherwise conical (or substantiallyconical and tapered) configuration. Specifically, an outer surface ofthe lower bushing may be tapered and an inner bore surface of the fronthead may be tapered as well mimicking the taper of the lower bushing. Amethod of removing the lower bushing from the front head is shown in theflowchart of FIG. 5.

Referring to FIG. 5, a flowchart 90 outlining the steps of removal ofthe lower bushing 28 from the front head 12 is shown, in accordance withat least some embodiments of the present disclosure. As shown, afterstarting at a step 92, the cross-pins 32 connecting the lower bushing 28to the front head 12 may first be removed at a step 94. Next, at a step96, the lower bushing 28 may be extended by a first distance (equal tothe distance D of FIG. 3A) out of the front head to facilitate removalof the lower bushing. Then, at a step 98, the lower bushing 28 may befurther extended away from the front head 12, such that beyond the firstdistance, the clearance between the front head and the lower bushingincreases to facilitate an easy removal of the lower bushing from thefront head. In at least some embodiments, after removing the lowerbushing 28 from the front head 12 by the first distance, the lowerbushing may even slide out of the front head by itself. Subsequent toremoving the lower bushing 28, it may be replaced or otherwise servicedin a manner deemed appropriate and may be installed back into the fronthead, as illustrated by step 100. The process then ends at a step 102.

By virtue of providing the tapered surfaces of the lower bushing and thefront head bore, and by mimicking the tapering of those surfaces, theclearance between those surfaces remain the same as the conventionaldesign during a working assembly, and the clearance increases only asthe lower bushing is pushed out for replacement or servicing, therebymaking the removal of the lower bushing easy. Easing the removal of thelower bushing not only saves time and labor cost, it also prevents theinadvertent damage of the front head (that may occur due to binding ofthe front head and the lower bushing), thereby preventing a completereplacement of the hydraulic hammer.

While only certain embodiments have been set forth, alternatives andmodifications will be apparent from the above description to thoseskilled in the art. These and other alternatives are consideredequivalents and within the spirit and scope of this disclosure and theappended claims.

What is claimed is:
 1. A hydraulic hammer, comprising: a front headdefining a first bore therein, an inner surface of the first bore havinga first taper; a lower bushing capable of being positioned within thefirst bore, an outer surface of the lower bushing having a second taper,the first taper substantially following the second taper, an inner wallof the lower bushing defining a second bore, and a clearance between theinner surface of the front head and the outer surface of the lowerbushing that exists when the lower bushing is in an installed statewithin the front head; and a work tool positioned and slidably retainedwithin the second bore for repetitive axial movement along an axis ofthe hydraulic hammer during operation of the hydraulic hammer.
 2. Thehydraulic hammer of claim 1, wherein the clearance between the fronthead and the lower bushing stays constant in the installed state of thelower bushing.
 3. The hydraulic hammer of claim 1, wherein the clearancebetween the front head and the lower bushing increases as the lowerbushing is removed from the front head.
 4. The hydraulic hammer of claim3, wherein the clearance increases from about one tenth of a millimeterwhen the bushing is in an installed position to about one millimeterwhen the bushing is removed axially from the installed position byapproximately 4″.
 5. The hydraulic hammer of claim 1, wherein the firsttaper ranges from about half a degree to about one degree from avertical line.
 6. The hydraulic hammer of claim 1, wherein the secondtaper ranges from about half a degree to about one degree from avertical line.
 7. The hydraulic hammer of claim 1, wherein the lowerbushing has a broader bottom portion and a narrower top portion.
 8. Thehydraulic hammer of claim 1, wherein the first bore has a broader bottombore portion and a narrower top bore portion.
 9. The hydraulic hammer ofclaim 1, wherein the lower bushing is tapered along a substantiallyentire length thereof.
 10. The hydraulic hammer of claim 9, wherein thefirst bore is tapered along the substantial entire length of the lowerbushing.
 11. The hydraulic hammer of claim 1, wherein the first taperand the second taper prevent binding of the lower bushing to the fronthead during removal.
 12. A hydraulic hammer, comprising: a front headdefining a first bore therein, an inner wall of the first bore having afirst tapered surface; a lower bushing capable of being positionedwithin the first bore, an outer wall of the lower bushing having asecond tapered surface, the first tapered surface substantiallyfollowing the second tapered surface, an inner wall of the lower bushingdefining a second bore such that the inner and outer walls of the lowerbushing are non-parallel to one another, and a clearance between theinner wall of the front head and the outer wall of the lower bushingexists when the lower bushing is in an installed state within the fronthead; and a work tool positioned and slidably retained within the secondbore for repetitive axial movement along an axis of the hydraulic hammerduring operation of the hydraulic hammer, and wherein the outer wallincludes a plurality of elongated recesses perpendicular to alongitudinal axis of the lower bushing and positioned substantially atninety degrees to one another.
 13. The lower bushing of claim 12 furtherhaving a narrower top portion and a broader bottom portion.
 14. Thelower bushing of claim 12, wherein the outer wall further includes aplurality of annular grooves, and a plurality of apertures extendingradially through the lower bushing from the outer wall to the innerwall, for lubricating a work tool disposed and slidable within the boredefined by the inner wall.